Trucks, boats, automobiles and other vehicles are commonly equipped with various signal communication devices such as radios for receiving broadcast radio frequency (RF) signals, processing the RF signals, and broadcasting audio information to passengers. Satellite digital audio radio (SDAR) services have become increasingly popular, offering digital radio service covering large geographic areas, such as North America. Other geographic areas, such as Europe, are also beginning to offer SDAR services. These services typically receive uplinked programming which, in turn, is provided to subscriber RF receivers via satellites or terrestrial receivers. Each subscriber to the service generally possesses a digital radio having an RF receiver and one or more antennas for receiving the digital broadcast and providing it to receivers coupled to the one or more antennas. When a digital broadcast signal is received by an antenna, it is typically amplified in a low-noise amplifier coupled to the antenna prior to being provided to additional processing circuitry in the receiver for decoding. This amplification process typically improves the quality of the received signal provided to the additional processing circuitry.
FIG. 1A generally illustrates one example of a conventional satellite digital audio radio system 90. In this system 90, satellite digital audio radio signals are received by an antenna 30. The received signals are amplified by a low-noise amplifier 32, filtered by a filter 34, and further amplified by amplifier 36 prior to being provided to SDAR processing circuitry 38. The received, amplified, and filtered satellite digital audio radio signals are further processed by SDAR processing circuitry 38 to extract audio and/or other data.
Global Positioning System (GPS) receivers are also becoming increasingly popular as vehicle accessories. GPS receivers are typically employed in systems to help vehicle drivers and/or passengers determine their location and navigate to various locations. GPS receivers typically receive signals from multiple satellites via an antenna or multiple antennas. By receiving signals from multiple satellites, the GPS receiver is able to determine the location of the GPS receiver, and therefore the vehicle in which the receiver is located, based on the received GPS signals. As with SDAR signals, the GPS signals received by a GPS antenna are typically amplified by a low-noise amplifier coupled to the antenna prior to being provided to additional processing circuitry in the GPS receiver for the calculation of GPS information. This amplification process typically improves the quality of the signal provided to the processing circuitry of the GPS receiver.
FIG. 1B generally illustrates one example of a conventional GPS system 92 for processing GPS signals. In this system 92, GPS signals are received by an antenna 40, amplified by a low-noise amplifier 42, filtered by a filter 44, and amplified again by an amplifier 46 prior to being provided to GPS processing circuitry 48. GPS processing circuitry 48 utilizes the amplified, filtered GPS signals to determine location information.
When both a conventional GPS system 92 and a conventional satellite digital audio radio system 90 are employed in the same vehicle, each of the systems typically requires its own low-noise amplifier (LNA) for amplifying the received GPS and SDAR signals, respectively. The requirement that each system have its own LNA increases the size of the systems and increases the total system cost.
What is needed is a system and method for cost-effectively amplifying both GPS and SDAR signals received by vehicle antennas.